Dome of Bio-Digester in Kenya under construction

Bio-Digesters in Kenya

When talking about bio-digesters in Kenya, there is over-reliance on biogas energy for cooking, heating, and electricity; particularly in the rural areas of Kenya. Wood fuel such as firewood and charcoal are the commonly used biomass fuel, thus impacting negatively on the environment and the users.

The Energy Policy 2004, explicitly pledged to promote domestic and institutional biogas technology, among other renewable energy sources. Several promotional efforts by the government, development partners, and private stakeholders have been made since the 1980s, but the spread of this technology has remained extremely low.

Luckily, change started to erupt where bio-digesters in Kenya became an option for waste management as well as providing renewable sources of energy.

So, in this article, we take a look at how bio-digesters in Kenya have been introduced in the country and how adaptable it is to the citizens of this country.

Bio-digesters in Kenya -- digging of a bio-digester pit.
Digging of a Bio-digester pit in Kenya

History of Bio-Digesters in Kenya

In 1957, Mr. Tim Hutchinson built the first biogas digester in Kenya. As a result, it provided all of the gas fuel and organic fertilizer that his coffee farm needed. He found the effluent as an excellent fertilizer and that its application to his coffee trees greatly improved productivity. One year later, he started constructing biogas digesters commercially, marketing the slurry as the main product with biogas as a useful by-product.

Between 1960 and 1986, Hutchinson’s company called Tunnel Engineering Ltd sold more than 130 small biogas units and 30 larger units all over the country. As a result, that brought its rise and spread in the county.

As of now, about 22,000 biogas plants have been installed in the country of which, 20,000 rely on livestock manure and the rest from crop waste — supported mainly from GIZ ( Deutsche Gesellschaft für Internationale Zusammenarbeit ). Over 90% of these biogas plants are domestic, others are institutional,  while the rest are in flower farms. The biogas digesters in learning institutions are majorly for training on biogas technology.

The government through the prison services has constructed 14 biogas plants in various correctional institutions across the country. This has in turn reduced wood fuel consumption by 30%. Kenya Biogas Programme which has since then been funded by the Dutch Government is supporting the expansion with Phase II targeting 26,500 biogas plants.

Three universities namely; Moi, Egerton, and Nairobi; have signed an agreement with the Italian Government of Kenya to developing model dairy farms, and Moi University will develop a center of excellence for biogas production from dairy offshoots. The Kenya Climate Smart Agriculture and Dairy NAMA Project have been developed and will support it.

Ring reinforcement of slab for bio-digester is ready
Ring reinforcement of slab for bio-digester

Why Bio-Digesters Failed to Pick Up Long Ago

You can blame it on illiteracy or maybe lack of funds and resources, but for a very long time, the idea of using bio-digesters was more like a plan than an implementation. Some of the reasons behind the failure to have this efficient waste management system is because of;

  • Poor maintenance — as long as people have no idea of how to manage the system, it will eventually fail.
  • Poor dissemination strategy by promoters — there weren’t any ways to know which system was original.
  • Poor planning and monitoring by promoters.
  • Poor construction or design leading to gas pressure problems.
  • Acceptance problems — people had to see to believe the true works of the bio-digester.
  • Limited water supply.
  • Weak technical support — still under lack of funds.

As long as these factors affected the implementation of bio-digesters in Kenya, there was no way to have this ecologically efficient waste management system.

Bio-digesters in Kenya -- casting of slab with ring reinforcement.

Challenges in the Bio-Digester Development

After numerous trials by the government to try and incorporate this new biotechnology there were still many problems and challenges. Some of these issues include;

  • High costs of installing the systems — the bio-digester needed 3 chambers with gas outlets as well as other things so it can fully function.
  • Inadequate capacity to install high volumes of biogas
  • High systems failures
  • Inadequate or lack of post-installation support — Normally a guarantee of 12 months had to be provided
  • Poor management and maintenance, possibly due to competing for land use with fodder plots.
  • Inadequate or lack of technology awareness.
  • Scarce and fragmented promotional activity.

These are only but a scale of the challenges faced. Because of that, people remained using septic tanks as it was something they already understood.

Low-Cost Bio-Digesters in Kenya

Attributed to our economy, many people are attracted to the use of low-cost bio-digesters in Kenya because they are cheaper to use and maintain. Especially with shipping container homes, the process of installing a bio-digester doesn’t take long hence, it aligns properly with the construction of the homes.

There are several types of bio-digesters that can be found at a low-cost. These types don’t require any active heating to speed up the process of decomposition or any mobile mixing mechanisms. Hence, it features very low investment costs, easy management, and low-cost maintenance. For this reason, they are accessible to low and large scale house developers as an inexpensive method to produce effective and renewable sources of energy.

One of the biggest advantages of using these digesters, besides being pocket-friendly, they are safe to use because the methane gas emitted from the biogas production is safe to be around. There’s no smoke emitted while cooking or using it as a form of electricity.

The bio-digesters have allowed many to have free and plenty of manure and water to use for their farming needs seeing that agriculture is one of the major markets in the country. The farmer uses this highly organic fertilizer to feed the crops for higher yields without having to pay thousands to buy manure.

So, low-cost bio-digesters in Kenya have added to the productivity in various industries including the petroleum sector as we see methane gases collected from biogas can be used to fuel cars, it just hasn’t been tapped by the government yet. This has aided in the ecological sector as we fight to control the environment and to stay away from pollutants and maintaining a recycling system. Similarly to shipping container homes.

The main advantage Kenya has seen with the use of bio-digesters is the improved ecological environment, which reduces rates of deforestation as people don’t go out to look for wood to use to cook, and reduced agrochemicals used to grown and yield crops in the farms. The impact is far greater than before and it only just begins.

Neck of a bio-digester
The neck of a Bio-Digester

Why Biogas is So Essential

You may be wondering what is the big fuss about this renewable source of energy. Well, first of all, it’s also important to note that biogas is generated naturally in swamps, where organic matter buried under sludge undergoes anaerobic digestion by bacteria. This gas, also known as marsh gas, has the cleanest fuel composition that any other. Making it the safest gas to use for your household.

The first bio-digesters were made in China around the mid-twentieth century. They were made of brick and looked like giant cooking pots, buried and sealed. Costs were high, due to the amount of work required to build this type of bio-digester, making this technology unaffordable for medium and small producers in rural areas with few resources.

In the 1970s industrial bio-digesters were designed in developed countries, where large amounts of organic material produced massive amounts of biogas, usually used to generate electricity. However, the technology was complex and the high investment costs made bio-digesters even less affordable for families with few resources and with few heads of cattle.

Moving on to the late ’80s, family bio-digesters were promoted as an appropriate technology for development, where investment costs are easily set off by a family in two or three years — this was the beginning of low-cost bio-digesters in Kenya and indeed the rest of the world.

Inlet chamber of a bio-digester

The Impact of the Use of Bio-Digesters in Kenya

For the longest time, the government of Kenya undertook agricultural activity as a way to promote and strategize for poverty reduction. Uncontrolled agricultural development leads to agricultural land expansion, new human settlements, misuse of chemicals and pollution, poor management of organic waste, and deforestation for fuel, cooking and productive activities.

Wood consumption in households for cooking lead not only to deforestation,  but also caused breathing problems, cancer, eye irritation, and other diseases, mainly in women and children. Especially since it is these two groups who had to bear the burden of finding and collecting firewood.

For this reason, agricultural development had to be accompanied by awareness, capacity building, technologies and regulations that promoted sustainable development. So, let’s say a family has two or three cows, or several pigs or a few dozen sheep, producing about 20 kilos of fresh manure per day, and has access to water for most of the year, a low-cost bio-digester can bring them multiple benefits. Some of which include;

  • Energy:- Biogas is mainly methane, much like the butane and propane gas sold in cylinders. It can be used for cooking, lighting, and heating.
  • Production:- The biol produced is a free natural fertilizer that improves crop yields by up to 30 percent. It can be poured directly onto the earth to stimulate seed growth or sprayed on leaves.
  • Family Health:- Burning biogas for cooking does not produce smoke, thus there is no black soot that could cause respiratory problems, or that covers kitchen walls.
  • Animal hygiene:- By putting the manure in a bio-digester, odors, foci of infection and flies will be eliminated. Furthermore, the decrease in the fly population has a direct impact on cows, reducing mastitis.
  • Environment:- If each family generates its own fuel for cooking there is no longer any need to cut down trees for firewood, hence protecting the environment.
  • Workload and cost:- Daily or weekly time spent by families to collect firewood or the money spent on the purchase of fuel in the rainy season, is replaced by the 20 minutes a day required for loading the bio-digester with fresh manure and water.
  • Sustainable Technology:– Since the technology used is simple, it is accessible to anyone, even those with no prior knowledge. It is enough to follow a few simple instructions to set up a bio-digester and understand the technology, daily operation, maintenance, and repair work. All materials are available locally, without the need to import anything from abroad.
  • Low investment:- You only give up a small amount of investment that will be paid back in less than three years.

A low-cost digester is a simple and accessible technology that has a positive effect on several aspects of family life, income, and production; though not a solution to all problems, it is a resource that brings many significant improvements.


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Dome of Bio-Digester in Kenya under construction

Low-cost Bio-digesters in Practice

A bio-digester is made of plastic; either tubular polyethylene, PVC or polyethylene geomembrane. Other materials include pipes for inputting manure and water and outputting biol. For biogas, a half-inch irrigation tubing can be used, together with common accessories such as taps, elbow joints, tees, etc. All these materials are usually available locally in any country.

Since bio-digesters are made of flexible plastic, they must be semi-buried in an open trench in the ground. The size of a family bio-digester will vary according to region but an area of at least 1m wide by 8m long will be required. In highlands, a bio-digester must be located under a shelter to protect it from the cold; remember to decompose, there must be a source of heat.


Usually, a family bio-digester produces around 700 liters of gas per day, enough to cook for about three hours. This gas — biogas — is produced naturally within the bio-digester as the manure ferments in the water.

Most noteworthy, biogas is very similar to bottle gas and can be used for cooking, lighting gas lamps, heating piglet hoods, among other things. Above all, cooking with biogas produces none of the smoke associated with firewood stoves, which can be harmful to one’s health.

Also, biogas is stored in a reservoir made of plastic, which acts as a cylinder. As a result, these reservoirs have to be placed near the kitchen and in a protected area under a roof. The reservoirs keep the biogas under pressure and each reservoir has enough for about an hour of cooking.

Final Thoughts on Bio-Digesters in Kenya

After reading this text, you must be convinced that in fact, investing in biotechnology has been such a beneficial process. Even with low investment, the product of this system is enough to cater to one’s family needs.

Bio-Digester in Kenya
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Bio-Digester in Kenya
For decades, many architectural projects included the use of septic tanks but not anymore. Bio-Digesters have become more on more common thanks to its eco-friendliness.
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Ishibox Limited
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